Lecture Notes on the Human Brain

General Overview

• The adult human brain contains more than a thousand million neurons.
• The cerebral cortex alone is estimated to have about $10^{27,83,000}$ synapses.
• The brain is divided into three main regions:
  • Forebrain (Prosencephalon)
  • Midbrain
  • Hindbrain

Focus on the Forebrain (Prosencephalon)

• Components:
  • Diencephalon
    • Formed of:
      • Thalamus
      • Hypothalamus
  • Cerebrum

Diencephalon

• Thalamus:

  • Largest part of the diencephalon.
  • Contains a cluster of nuclei.
  • Conducts most sensory inputs to the cerebral cortex.
  • Exons carrying auditory, visual, and other sensory information synapse with specific nuclei here.
  • Influences mood and general body movements due to strong emotions such as fear or anger.

• Hypothalamus:

  • Contains small nuclei and nerve tracts.
  • Features mammillary bodies involved in olfactory reflexes and emotional responses to odors.
  • Connected to the posterior pituitary (neurohypophysis) via the infundibulum.
  • Controls secretions of the pituitary gland.
  • Receives inputs from sensory systems like tongue, nose, and external genitalia.
  • Associated with emotional and mood relationships; provides a relaxed feeling.
  • Responsible for feelings such as satisfaction after a meal, rage, and fear.
  • Coordinates responses to the sleep-wake cycle with other brain regions.